CVE-2002-0854 in Linux
Summary
by MITRE
Buffer overflows in ISDN Point to Point Protocol (PPP) daemon (ipppd) in the i4l package on SuSE 7.3, 8.0, and possibly other operating systems, may allow local users to gain privileges.
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Analysis
by VulDB Data Team • 06/08/2018
The vulnerability identified as CVE-2002-0854 represents a critical buffer overflow condition within the ISDN Point to Point Protocol daemon known as ipppd, which is part of the i4l package distributed with SuSE Linux versions 7.3 and 8.0. This daemon operates as a crucial component for handling ISDN (Integrated Services Digital Network) connections, specifically managing the Point to Point Protocol negotiations and data transmission over digital telephone lines. The flaw manifests in the daemon's improper handling of input data during the PPP negotiation process, creating opportunities for malicious exploitation that could lead to privilege escalation. The vulnerability exists because the daemon fails to properly validate the length of incoming data buffers, particularly when processing configuration parameters and protocol control messages from remote ISDN peers.
The technical implementation of this buffer overflow occurs within the daemon's input processing functions where it reads and parses data from ISDN connections without adequate bounds checking. When the ipppd daemon receives specially crafted PPP control packets or configuration data, it stores this information into fixed-size buffers without verifying that the incoming data exceeds the allocated buffer capacity. This classic buffer overflow condition allows a local attacker to overwrite adjacent memory locations, potentially corrupting the program's execution flow or injecting malicious code. The vulnerability is particularly concerning because it operates within a privileged daemon process that typically runs with elevated system permissions, making successful exploitation capable of granting the attacker root-level access to the affected system. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, while the ATT&CK framework would categorize this under T1068: Exploitation for Privilege Escalation.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it creates a persistent backdoor mechanism that could be exploited by attackers who gain access to the system's local network interfaces or ISDN connections. Since the daemon typically runs with root privileges and manages critical network connectivity functions, successful exploitation could provide attackers with complete system control, including the ability to modify system files, install malicious software, or establish persistent access through the ISDN infrastructure. The vulnerability affects systems running SuSE 7.3 and 8.0, but given the nature of the code and similar patterns found in other network daemons of that era, it is highly probable that other Linux distributions and versions using the same i4l package components would be similarly vulnerable. Network administrators should note that this vulnerability could be exploited by anyone with access to the local system or ISDN network connections, making it particularly dangerous in multi-user environments where local access might be more readily available than previously assumed.
Mitigation strategies for this vulnerability should prioritize immediate patching of the affected i4l package through official SuSE security updates or manual patching of the ipppd daemon source code. System administrators should also implement network segmentation to limit access to ISDN interfaces and disable unnecessary ISDN services when not actively required. Additional defensive measures include monitoring for unusual PPP protocol activity and implementing strict access controls on system interfaces that might allow local users to interact with the daemon. The vulnerability demonstrates the importance of input validation and proper bounds checking in network daemon implementations, particularly those handling untrusted data from remote sources. Organizations should also consider implementing network intrusion detection systems to identify potential exploitation attempts and conduct regular security audits of network services to identify similar buffer overflow vulnerabilities in other system components. The remediation process should include thorough testing of patched systems to ensure that the security update does not introduce compatibility issues with existing ISDN network configurations or applications that depend on the ipppd daemon functionality.